gpio: gpio-rockchip: parse gpio-ranges for bank id

Use the new devicetree property of gpio-ranges to determine the GPIO
bank ID. Preserve the "old" way of doing things too, so that boards
can be migrated and tested gradually (I only have a 3566 and 3326 to
test).

Signed-off-by: Chris Morgan <macromorgan@hotmail.com>
Reviewed-by: Kever Yang <kever.yang@rock-chips.com>